There needs to be a word for the prickly, pompous anger of Cardinal Keith O’Brien and I suggest harrumphability. When he compares gay marriage with the reintroduction of slavery he makes the whole of Christian ethics look like some sonorous, rust-riddled wreck plunging towards the seabed, while gouts of foul air escape towards the surface as it all breaks up.

So, in a spirit of fairness, I want to see if there is anything to salvage from the wreck. Could there be a Catholic position on gay marriage that didn’t look as if it were driven by homophobia?

One answer is suggested by Archbishop Vincent Nichols, who runs the Catholic church in England and Wales. He’s not, one notes, a cardinal, as archbishops of Westminster usually are, and as O’Brien is. Some people say this is because he had a reputation as a liberal, others that his ambition was too open. In any case, he seems to be riding the waves of secularity rather more gracefully than the ironclad cardinal. Only last week, he gave permission for the “gay masses” in Soho to continue for another five years, though naturally it is assumed that no one who goes there could possibly be having sex, or, if they are, could feel good about the practice.

He also told me, in our recent interview, that he was “singing from the same hymn sheet” as the cardinal. That is possible but though the words are the same, the tune and the arrangements are very different.

Nichols went out of his way to mention the similarities between remarried Catholics and gay ones. Neither can really be married, in Catholic teaching. Nor should either group have sex, according to the Vatican. This will come as bad news to prominent Catholics such as Cristina Odone (married to a divorced man) and Clifford Longley (on his second wife). Yet both of these journalists are quite rightly regarded as adornments to the English Catholic church.

Admittedly, there is for straight people always the option of having the first marriage annulled, which for some reason gets easier the richer and more powerful you become. This is one of those loopholes that makes the surrounding law look even more unjust.

But apart from that, the condition of gay and of remarried Catholics is pretty much the same and the scriptural warrant for rejecting divorce is quite a lot stronger than the evidence for damning all gay people. I think it’s pretty clear that the authors of the Bible would have been horrified by gay marriage, but it is nowhere explicitly denounced the way that Jesus denounced divorce.

Despite this, the policy of the Catholic church, in England and Wales at least, is the eminently sensible and humane one of doing everything possible to keep divorced and remarried couples as part of their parishes, attending church regularly. It may be that this is driven more by necessity, or horse sense, than humanity: if only Catholics who fully accepted the church’s teaching on sex went to churches they would all empty. Nonetheless, the argument from humanity would be widely accepted. In Christian language, remarried couples can be a means of grace to one another.

And, if remarried couples can, why can’t gay couples, too?

This is the question that, I think, convicts O’Brien of something more than old age and pugnacity. Last week, as an experiment, I asked on Twitter whether religious conservatives thought marriage better defended by banning straight divorce or gay marriage. Most of those who responded said the question was unfair and both were wrong. But the three or four people who answered the question honestly all replied “divorce”.

No one is going to make divorce more difficult in the foreseeable future. But even if they were, the argument for remarriage is not just one of harm reduction. It’s about increasing the good in the world. Even if we don’t consider the needs of children (and I think a loving step-parent is better than none at all, just as an unloving one is worse) a remarried couple can be a source of strength and consolation to one another in a way quite easily distinguished from friendship. What no Catholic can convincingly do is explain why the case must be different for gay people. They know – we all do – about remarried couples from experience, if in a rather inarticulate way.

But until the Catholic church campaigns against civil marriage for straight people with the same fervour as it campaigns against gay marriage, it’s obvious that O’Brien is not just bigoted and wrong, but wrong for all the bigoted wrong reasons.